The semantic of 'LTMS.TmSynLkd' as modelled in 'ClockSyncLockingKind' is not clear.
The description text of 'ClockSyncLockingKind' should be improved.
The description text of 'LTMS.TmSynLkd' should be improved. Not been synchronized by "LocalAreaClock” does not mean that the IED is synchronized by “GlobalAreaClock” – the IED can also be synchronized by “InternalClock”.
Proposal
The description texts of the values of 'ClockSyncLockingKind' should be improved to explain the behaviour:
During undisturbed global synchronization, the IED will tell “Locked”.
Once a loss of the clock source was detected, the IED will tell, one message after the other, with a time stamp each,
- “the locked state has been lost for 10 s”
- “the locked state has been lost for 100 s”
- “the locked state has been lost for 1000 s” and finally
- “the locked state has been lost for more than 1000 s”
which will be kept until the clock source is available again.
'LTMS.TmSynLkd': Propose to change a part of the description text to:
"... ('TmSyn' value is 'GlobalAreaClock') ...". Propose to add a sentence which helps understanding that the value of 'LTMS.TmSynLkd' will change with the duration of the loss of global synchronization.
Discussion
Created
Status
small correction of the proposal to be more precise:
Table 220 - Literals of ClockSyncLockingKind
enumeration item : value : description
Locked : 1 : Time synchronisation is locked to its external reference.
Unlocked10s : 2 : Time synchronisation is unlocked less than 10s.
Unlocked100s : 3 : Time synchronisation is unlocked 10s or more but less than 100s.
Unlocked1000s : 4 : Time synchronisation is unlocked 100s or more but less than 1000s.
UnlockedMoreThan1000s : 5 : Time synchronization is unlocked more than 1000s.
07 Feb 26
Discussion (red)
I would like to propose the following as an approach for this tissue to be more precise and to improve the current description in 7-4:
Kind of clock synchronisation locking.
Specifies the clock synchronization locking state and, where applicable, the unlock duration classification.
“Locked” means the clock is synchronized to its external reference within a defined time inaccuracy threshold. The reference may be local (non-UTC-traceable) or global (UTC-traceable). Determined by ClockSyncKind.
Note: Profile-specific interpretation: For synchrophasor applications (IEC 61850-90-5, IEEE C37.118.2), “Locked” typically implies UTC traceability and may include quality classifications based on unlock duration.
Table 220 - Literals of ClockSyncLockingKind
enumeration item : value : description
Locked : 1 : Time synchronisation is locked to its external reference.
Unlocked10s : 2 : Time synchronisation is unlocked less than 10s.
Unlocked100s : 3 : Time synchronisation is unlocked 10s or less than 100s.
Unlocked1000s : 4 : Time synchronisation is unlocked 100s or less than 1000s.
UnlockedMoreThan1000s : 5 : Time synchronisation is unlocked more than 1000s.
Good point, but if you take IEC 61850-90-5 and IEEE C37.118 in consideration, there is an actual difference and might have been the intention for the enum which we should consider.
C37.118.2 - e.g. Table A.5
sync locked or unlocked < 10 s (best quality)
10 s = unlocked time < 100 s
100 s < unlock time = 1000 s
unlocked time > 1000 s
21 Oct 25
Discussion (red)
We could consider to deprecate the last enumeration value. There is no real difference between the meanings of value "4" and "5".
Even if "4" was issued exactly when reaching 1000s, the add-on information of "5" is small.
I assume that we will keep it for backward compatibility reasons.
20 Oct 25
Discussion (red)
Open for discussion.
I agree with the content of this tissue and the former comment.
Proposal: Handling this issue as an editorial change.
Summary: Improvement/editorial change of
- desc. text of DO "LTMS.TmSynLkd"
- clause 7.2.12 "Clock synchronisation locking (ClockSyncLockingKind enumeration)" and its table "Table 220 – Literals of ClockSyncLockingKind"
to provide a better and more clear understanding and definition.
20 Oct 25
Discussion (red)
I agree to improve the description and enum values.
The current text had been copied from TR IEC 61850-90-5 into edition 2.1 of part 7-4. But today's understanding should be be incooperated.